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- 1. Preface
- 2. Setup Environments
- 2.1. Hardware
- 2.2. Environment (Just needed if you are running with Instructor support)
- 2.3. Docker Toolbox
- 2.4. Software
- 2.5. Git Client
- 2.6. Maven
- 2.7. VirtualBox (For Linux users only)
- 2.8. Vagrant (For Kubernetes)
- 2.9. Docker Machine Installation (For Linux users)
- 2.10. Create Lab Docker Host (For Windows and Mac)
- 2.11. Docker Client (For Linux users)
- 2.12. WildFly
- 2.13. JBoss Developer Studio 9.0.0.GA
- 3. Docker Basics
- 4. Run Container
- 5. Build an Image
- 6. Deploy Java EE 7 Application (Pre-Built WAR)
- 7. Deploy Java EE 7 Application (Container Linking)
- 8. Build and Deploy Java EE 7 Application
- 9. Multiple Containers Using Docker Compose
- 10. Deploy Application on Kubernetes Cluster
- 10.1. Install Kubernetes
- 10.2. Key Components
- 10.3. Start Kubernetes Cluster
- 10.4. Deploy Java EE Application (multiple configuration files)
- 10.5. Deploy Java EE Application (one configuration file)
- 10.6. Rescheduling Pods
- 10.7. Scaling Pods
- 10.8. Application Logs
- 10.9. Delete Kubernetes Resources
- 10.10. Stop Kubernetes Cluster
- 10.11. Debug Kubernetes Master
- 11. Common Docker Commands
- 12. Troubleshooting
- 13. References
1. Preface
Containers are enabling developers to package their applications (and underlying dependencies) in new ways that are portable and work consistently everywhere? On your machine, in production, in your data center, and in the cloud. And Docker has become the de facto standard for those portable containers in the cloud.
Docker is the developer-friendly Linux container technology that enables creation of your stack: OS, JVM, app server, app, and all your custom configuration. So with all it offers, how comfortable are you and your team taking Docker from development to production? Are you hearing developers say, “But it works on my machine!” when code breaks in production?
This lab offers developers an intro-level, hands-on session with Docker, from installation, to exploring Docker Hub, to crafting their own images, to adding Java apps and running custom containers. It will also explain how to use Swarm to orchesorchestrate these containers together. This is a BYOL (bring your own laptop) session, so bring your Windows, OSX, or Linux laptop and be ready to dig into a tool that promises to be at the forefront of our industry for some time to come.
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Note
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Latest content of this lab is always at https://github.com/redhat-developer/docker-java |
2. Setup Environments
This section describes what, how, and where to install the software needed for this lab. This lab is designed for a BYOL (Brying Your Own Laptop) style hands-on-lab.
2.1. Hardware
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Operating System: Windows 7 (SP1), Mac OS X (10.8 or later), Fedora (21 or later)
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Memory: At least 4 GB+, preferred 8 GB
2.2. Environment (Just needed if you are running with Instructor support)
2.2.1. DNS Server setup Windows
Go to the adapter settings of your pc’s and open the Wireless Network Connection Properties Dialogue. Edit the IPv4 Properties and add the instructor IP (!) as a primary DNS server.
Switch to the cmd and ping classroom.example.com to verify it works.
2.2.2. DNS Server setup Linux/Mac OS
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Edit
/etc/resolv.conf(Mac OS or Linux) and leave it as:
nameserver <INSTRUCTOR IP ADDRESS>
2.3. Docker Toolbox
The Docker Toolbox is an installer to quickly and easily install and setup a Docker environment on your computer. Available for both Windows and Mac, the Toolbox installs Docker Client, Machine, Compose, Kitematic and VirtualBox.
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What’s in the toolbox:
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Docker Client
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Docker Machine
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Docker Compose
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Docker Kitematic
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Downloads are available
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from Internet: https://www.docker.com/docker-toolbox .
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from Instructor: http://classroom.example.com:8082/downloads/docker/ .
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2.4. Software
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Java: Oracle JDK 8u45 or later
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Web Browser
2.5. Git Client
Install Git Client as explained at: https://git-scm.com/book/en/v2/Getting-Started-Installing-Git
You can find GIT for Windows at: http://classroom.example.com:8082/downloads/Git-2.6.2-64-bit.exe
2.6. Maven
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Download Apache Maven…
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from Internet: https://maven.apache.org/download.cgi
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from Instructor: http://classroom.example.com:8082/downloads/apache-maven-3.3.3-bin.zip.
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Unzip to a directory of your choice and add it to the
PATH.
2.7. VirtualBox (For Linux users only)
Docker currently runs natively on Linux. It can be configured to run in a virtual machine on Mac or Windows. This is why Virtualbox is a requirement for Mac or Windows. Docker Toolbox already includes Virtualbox but if you are a Linux user and wants to simulate multiple nodes in a Docker cluster, you must install VirtualBox.
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Downloads are available
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from Internet: https://www.virtualbox.org/wiki/Downloads .
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from Instructor: http://classroom.example.com:8082/downloads/virtualbox/ .
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Warning
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Linux Users
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2.8. Vagrant (For Kubernetes)
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Download Vagrant
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from Internet: https://www.vagrantup.com/downloads.html
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from Instructor: http://classroom.example.com:8082/downloads/vagrant/ and install.
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2.9. Docker Machine Installation (For Linux users)
Docker Machine makes it really easy to create Docker hosts on your computer, on cloud providers and inside your own data center. It creates servers, installs Docker on them, then configures the Docker client to talk to them.
# Linux - From Internet
curl -L https://github.com/docker/machine/releases/download/v0.5.0/docker-machine_linux-amd64.zip >machine.zip && \
unzip machine.zip && \
rm machine.zip && \
sudo mv -f docker-machine* /usr/local/bin
# Linux - From Instructor
curl -L http://classroom.example.com:8082/downloads/docker/docker-machine_linux-amd64.zip >machine.zip && \
unzip machine.zip && \
rm machine.zip && \
sudo mv -f docker-machine* /usr/local/bin
2.10. Create Lab Docker Host (For Windows and Mac)
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If you are running this lab without an Instructor, create the Docker Host using the following command:
docker-machine create --driver=virtualbox lab eval "$(docker-machine env lab)"
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Or Create Docker Host to be used in the lab with an Instructor:
docker-machine create --driver=virtualbox --virtualbox-boot2docker-url=http://classroom.example.com:8082/downloads/boot2docker.iso --engine-insecure-registry=classroom.example.com:5000 lab eval "$(docker-machine env lab)"
Use the following command on Windows:
docker-machine env lab --shell cmd
And then execute all the set commands.
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To make it easier to start/stop the containers, an entry is added into the host mapping table of your operating system. Find out the IP address of your machine:
docker-machine ip lab
This will provide the IP address associated with the Docker Machine created earlier.
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Edit
C:\Windows\System32\drivers\etc\hosts(Windows) or/etc/hosts(Mac OS or Linux) and add:
<IP ADDRESS> dockerhost
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Check if the entry is working:
ping dockerhost
2.11. Docker Client (For Linux users)
Docker Client is used to communicate with Docker Host.
# Linux - From Internet
sudo curl -L https://get.docker.com/builds/Linux/x86_64/docker-latest -o /usr/local/bin/docker
sudo chmod +x /usr/local/bin/docker
# Linux - From Instructor
sudo curl -L http://classroom.example.com:8082/downloads/docker/docker-latest-linux -o /usr/local/bin/docker
sudo chmod +x /usr/local/bin/docker
Check if the client is working by executing:
docker ps
Which will return an empty list of containers working. If you get an error message, make sure to have put the docker client into a folder that is contained in your path expression and that you executed the "docker-machine env lab" command according to your operatingsystem.
2.12. WildFly
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Download WildFly 9.0.2
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from Internet: http://download.jboss.org/wildfly/9.0.2.Final/wildfly-9.0.2.Final.zip .
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from Instructor: http://classroom.example.com:8082/downloads/wildfly-9.0.2.Final.zip .
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Install it by extracting the archive.
2.13. JBoss Developer Studio 9.0.0.GA
To install JBoss Developer Studio stand-alone, complete the following steps:
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From Internet: http://www.jboss.org/download-manager/file/jboss-devstudio-9.0.0.GA-standalone_jar.jar .
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From Instructor: http://classroom.example.com:8082/downloads/jboss-devstudio-9.0.0.GA-installer-standalone.jar .
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Start the installer as:
java -jar <JAR FILE NAME>
Follow the on-screen instructions to complete the installation process.
3. Docker Basics
PURPOSE: This chapter introduces the basic terminology of Docker.
Docker is a platform for developers and sysadmins to develop, ship, and run applications. Docker lets you quickly assemble applications from components and eliminates the friction that can come when shipping code. Docker lets you get your code tested and deployed into production as fast as possible.
Docker simplifies software delivery by making it easy to build and share images that contain your application’s entire environment, or application operating system.
What does it mean by an application operating system ?
Your application typically require a specific version of operating system, application server, JDK, database server, may require to tune the configuration files, and similarly multiple other dependencies. The application may need binding to specific ports and certain amount of memory. The components and configuration together required to run your application is what is referred to as application operating system.
You can certainly provide an installation script that will download and install these components. Docker simplifies this process by allowing to create an image that contains your application and infrastructure together, managed as one component. These images are then used to create Docker containers which run on the container virtualization platform, provided by Docker.
Main Components of Docker
Docker has three main components:
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Images are build component of Docker and a read-only template of application operating system.
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Containers are run component of Docker, and created from, images.Containers can be run, started, stopped, moved, and deleted.
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Images are stored, shared, and managed in a registry, the distribution component of Docker. The publically available registry is known as Docker Hub (available at http://hub.docker.com).
In order for these three components to work together, there is Docker Daemon that runs on a host machine and does the heavy lifting of building, running, and distributing Docker containers. In addition, there is Client that is a Docker binary which accepts commands from the user and communicates back and forth with the daemon.
Client communicates with Daemon, either co-located on the same host, or on a different host. It requests the Daemon to pull an image from the repository using pull command. The Daemon then downloads the image from Docker Hub, or whatever registry is configured. Multiple images can be downloaded from the registry and installed on Daemon host. Images are run using run command to create containers on demand.
How does a Docker Image work?
We’ve already seen that Docker images are read-only templates from which Docker containers are launched. Each image consists of a series of layers. Docker makes use of union file systems to combine these layers into a single image. Union file systems allow files and directories of separate file systems, known as branches, to be transparently overlaid, forming a single coherent file system.
One of the reasons Docker is so lightweight is because of these layers. When you change a Docker image—for example, update an application to a new version— a new layer gets built. Thus, rather than replacing the whole image or entirely rebuilding, as you may do with a virtual machine, only that layer is added or updated. Now you don’t need to distribute a whole new image, just the update, making distributing Docker images faster and simpler.
Every image starts from a base image, for example ubuntu, a base Ubuntu image, or fedora, a base Fedora image. You can also use images of your own as the basis for a new image, for example if you have a base Apache image you could use this as the base of all your web application images.
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Note
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By default, Docker obtains these base images from Docker Hub. |
Docker images are then built from these base images using a simple, descriptive set of steps we call instructions. Each instruction creates a new layer in our image. Instructions include actions like:
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Run a command
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Add a file or directory
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Create an environment variable
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Run a process when launching a container
These instructions are stored in a file called a Dockerfile. Docker reads this Dockerfile when you request a build of an image, executes the instructions, and returns a final image.
How does a Container work?
A container consists of an operating system, user-added files, and meta-data. As we’ve seen, each container is built from an image. That image tells Docker what the container holds, what process to run when the container is launched, and a variety of other configuration data. The Docker image is read-only. When Docker runs a container from an image, it adds a read-write layer on top of the image (using a union file system as we saw earlier) in which your application can then run.
3.1. Docker Machine (For Windows and Mac)
Machine makes it really easy to create Docker hosts on your computer, on cloud providers and inside your own data center. It creates servers, installs Docker on them, then configures the Docker client to talk to them.
Once your Docker host has been created, it then has a number of commands for managing containers:
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Start, stop, restart container
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Upgrade Docker
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Configure the Docker client to talk to a host
You used Docker Machine already during the attendee setup. We won’t need it too much further on. But if you need to create hosts, it’s a very handy tool to know about. From now on we’re mostly going to use the docker client.
Find out more about the details at the Docker Machine Website.
Check if docker machine is working:
docker-machine -v
It shows the output similar to the one shown below:
docker-machine version 0.5.0 (04cfa58)
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Note
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The exact version may differ based upon how recently the installation was performed. |
3.2. Docker Client
The client communicates with the demon process on your host and let’s you work with images and containers.
Check if your client is working using the following command:
docker -v
It shows the output similar to the following:
Docker version 1.9.0, build 76d6bc9
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Note
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The exact version may differ based upon how recently the installation was performed. |
The most important options you’ll be using frequently are:
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run- runs a container -
ps- lists containers -
stop- stops a container -
rm- Removes a container
Get a full list of available commands with
docker
A more comprehensive list of commands is also available in Common Docker Commands.
3.3. Verify Docker Configuration
Check if your Docker Host is running:
docker-machine ls
You should see the output similar to:
NAME ACTIVE DRIVER STATE URL SWARM
lab virtualbox Running tcp://192.168.99.101:2376
This machine is shown in “Running” state. If the machine state is stopped, start it with:
docker-machine start lab
After it is started you can find out IP address of your Docker Host with:
docker-machine ip lab
We already did this during the setup document, remember? So, this is a good chance to check, if you already added this IP to your hosts file.
Type:
ping dockerhost
and see if this resolves to the IP address that the docker-machine command printed out. You should see an output as:
> ping dockerhost
PING dockerhost (192.168.99.101): 56 data bytes
64 bytes from 192.168.99.101: icmp_seq=0 ttl=64 time=0.394 ms
64 bytes from 192.168.99.101: icmp_seq=1 ttl=64 time=0.387 ms
If it does, you’re ready to start with the lab.
4. Run Container
The first step in running any application on Docker is to run a container from an image. There are plenty of images available from the official Docker registry (aka Docker Hub). To run any of them, you just have to ask the Docker Client to run it. The client will check if the image already exists on Docker Host. If it exists then it’ll run it, otherwise the host will download the image and then run it.
4.1. Pull Image
Let’s first check, if any images are available:
docker images
At first, this list is empty.
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
Now, let’s get a vanilla jboss/wildfly image:
#From Internet
docker pull jboss/wildfly:latest
#From Instructor
docker pull classroom.example.com:5000/wildfly:latest
By default, docker images are retrieved from Docker Hub. In our case, we’re providing a so called private registry via the instructor laptop.
You can see, that Docker is downloading the image with it’s different layers.
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Note
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In a traditional Linux boot, the Kernel first mounts the root File System as read-only, checks its integrity, and then switches the whole rootfs volume to read-write mode. When Docker mounts the rootfs, it starts read-only, as in a traditional Linux boot, but then, instead of changing the file system to read-write mode, it takes advantage of a union mount to add a read-write file system over the read-only file system. In fact there may be multiple read-only file systems stacked on top of each other. Consider each one of these file systems as a layer. At first, the top read-write layer has nothing in it, but any time a process creates a file, this happens in the top layer. And if something needs to update an existing file in a lower layer, then the file gets copied to the upper layer and changes go into the copy. The version of the file on the lower layer cannot be seen by the applications anymore, but it is there, unchanged. We call the union of the read-write layer and all the read-only layers a union file system. Figure 3. Docker Layers
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In our particular case, the jboss/wildfly image extends the jboss/base-jdk:8 image which adds the OpenJDK distribution on top of the jboss/base image. The base image is used for all JBoss community images. It provides a base layer that includes:
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A jboss user (uid/gid 1000) with home directory set to
/opt/jboss -
A few tools that may be useful when extending the image or installing software, like unzip.
The “jboss/base-jdk:8” image adds:
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OpenJDK 8 distribution
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Adds a
JAVA_HOMEenvironment variable
When the download is done, you can list the images again and will see the following:
docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
jboss/wildfly latest 7688aaf382ab 6 weeks ago 581.4 MB
4.2. Run Container
For now, all we did is pull the container description (aka image) down to our local laptops. Now we want to actually run an instance of the image as a so called "container".
4.2.1. Interactive Container
Typically container run in the background. They are launched and forgotten. And this is the default behaviour for Docker. But there is a way we can make them behave like an instance with an interactive console. To run the WildFly container in an interactive mode.
#From Internet
docker run -it jboss/wildfly
#From Instructor
docker run -it classroom.example.com:5000/wildfly
This will show the output as:
=========================================================================
JBoss Bootstrap Environment
JBOSS_HOME: /opt/jboss/wildfly
JAVA: /usr/lib/jvm/java/bin/java
JAVA_OPTS: -server -XX:+UseCompressedOops -server -XX:+UseCompressedOops -Xms64m -Xmx512m -XX:MaxPermSize=256m -Djava.net.preferIPv4Stack=true -Djboss.modules.system.pkgs=org.jboss.byteman -Djava.awt.headless=true
=========================================================================
OpenJDK 64-Bit Server VM warning: ignoring option MaxPermSize=256m; support was removed in 8.0
17:02:58,000 INFO [org.jboss.modules] (main) JBoss Modules version 1.4.3.Final
17:02:58,251 INFO [org.jboss.msc] (main) JBoss MSC version 1.2.6.Final
17:02:58,311 INFO [org.jboss.as] (MSC service thread 1-2) WFLYSRV0049: WildFly Full 9.0.2.Final (WildFly Core 1.0.2.Final) starting
17:02:59,558 INFO [org.jboss.as.controller.management-deprecated] (ServerService Thread Pool -- 11) WFLYCTL0028: Attribute 'job-repository-type' in the resource at address '/subsystem=batch' is deprecated, and may be removed in future version. See the attribute description in the output of the read-resource-description operation to learn more about the deprecation.
17:02:59,560 INFO [org.jboss.as.controller.management-deprecated] (ServerService Thread Pool -- 3) WFLYCTL0028: Attribute 'enabled' in the resource at address '/subsystem=datasources/data-source=ExampleDS' is deprecated, and may be removed in future version. See the attribute description in the output of the read-resource-description operation to learn more about the deprecation.
...
17:03:00,610 INFO [org.wildfly.extension.undertow] (MSC service thread 1-2) WFLYUT0006: Undertow HTTP listener default listening on /0.0.0.0:8080
17:03:00,715 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-2) WFLYJCA0001: Bound data source [java:jboss/datasources/ExampleDS]
17:03:00,881 INFO [org.jboss.ws.common.management] (MSC service thread 1-1) JBWS022052: Starting JBoss Web Services - Stack CXF Server 5.0.0.Final
17:03:00,891 INFO [org.jboss.as.server.deployment.scanner] (MSC service thread 1-2) WFLYDS0013: Started FileSystemDeploymentService for directory /opt/jboss/wildfly/standalone/deployments
17:03:01,131 INFO [org.jboss.as] (Controller Boot Thread) WFLYSRV0060: Http management interface listening on http://127.0.0.1:9990/management
17:03:01,133 INFO [org.jboss.as] (Controller Boot Thread) WFLYSRV0051: Admin console listening on http://127.0.0.1:9990
17:03:01,138 INFO [org.jboss.as] (Controller Boot Thread) WFLYSRV0025: WildFly Full 9.0.2.Final (WildFly Core 1.0.2.Final) started in 3431ms - Started 203 of 379 services (210 services are lazy, passive or on-demand)
This shows that the server started correctly, congratulations!
The switches do the following: -i allows to interact with the STDIN and -t attach a TTY to the process. Switches can be combined together and used as -it.
Hit Ctrl+C to stop the container.
4.2.2. Detached Container
Restart the container in detached mode:
#From Internet
docker run --name mywildfly -d jboss/wildfly
#From Instructor
docker run --name mywildfly -d classroom.example.com:5000/wildfly
972f51cc8422eec0a7ea9a804a55a2827b5537c00a6bfd45f8646cb764bc002a
-d, instead of -it, runs the container in detached mode.
The output is the unique id assigned to the container. You can use it to refer to the container in various contexts. Check the logs as:
> docker logs 972f51cc8422eec0a7ea9a804a55a2827b5537c00a6bfd45f8646cb764bc002a
=========================================================================
JBoss Bootstrap Environment
JBOSS_HOME: /opt/jboss/wildfly
. . .
We can check it by issuing the docker ps command which retrieves the images process which are running and the ports engaged by the process:
> docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
7da1c7614edf jboss/wildfly "/opt/jboss/wildfly/ About a minute ago Up About a minute 8080/tcp mywildfly
Noticed the "NAMES" column? This is a quick way of refering to your container. Let’s try to look at the logs again:
docker logs mywildfly
That looks easier.
Also try docker ps -a to see all the containers on this machine.
4.3. Run Container with Default Port
Startup log of the server shows that the server is located in the /opt/jboss/wildfly. It also shows that the public interfaces are bound to the 0.0.0.0 address while the admin interfaces are bound just to localhost. This information will be useful to learn how to customize the server.
docker-machine ip <machine-name> gives us the Docker Host IP address and this was already added to the hosts file. So, we can give it another try by accessing: http://dockerhost:8080. However, this will not work either.
If you want containers to accept incoming connections, you will need to provide special options when invoking docker run. The container, we just started, can’t be accessed by our browser. We need to stop it again and restart with different options.
docker stop mywildfly
Restart the container as:
#From Internet
docker run --name mywildfly-exposed-ports -d -P jboss/wildfly
#From Instructor
docker run --name mywildfly-exposed-ports -d -P classroom.example.com:5000/wildfly
-P map any exposed ports inside the image to a random port on the Docker host. This can be verified as:
> docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
7f41a5a0cfd6 jboss/wildfly "/opt/jboss/wildfly/ 52 seconds ago Up 52 seconds 0.0.0.0:32768->8080/tcp mywildfly-exposed-ports
The port mapping is shown in the PORTS column. Access the WildFly server at http://dockerhost:32768. Make sure to use the correct port number as shown in your case.
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Note
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Exact port number may be different in your case. |
4.4. Run Container with Specified Port
Lets stop the previously running container as:
docker stop mywildfly-exposed-ports
Restart the container as:
#From Internet
docker run --name mywildfly-mapped-ports -d -p 8080:8080 jboss/wildfly
#From Instructor
docker run --name mywildfly-mapped-ports -d -p 8080:8080 classroom.example.com:5000/wildfly
The format is -p hostPort:containerPort. This option maps container ports to host ports and allows other containers on our host to access them.
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Note
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Docker Port Mapping
Port exposure and mapping are the keys to successful work with Docker. See more about networking on the Docker website Advanced Networking |
Now we’re ready to test http://dockerhost:8080 again. This works with the exposed port, as expected.
Lets stop the previously running container as:
docker stop mywildfly-mapped-ports
4.5. Stop Container
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Stop a specific container:
docker stop <CONTAINER ID>
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Stop all the running containers
docker stop $(docker ps -q)
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Stop only the exited containers
docker ps -a -f "exited=-1"
4.6. Remove Container
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Remove a specific container:
docker rm 0bc123a8ece0
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Remove containers meeting a regular expression
docker ps -a | grep wildfly | awk '{print $1}' | xargs docker rm
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Remove all containers, without any criteria
docker rm $(docker ps -aq)
4.7. Enabling WildFly Administration
Default WildFly image exposes only port 8080 and thus is not available for administration using either the CLI or Admin Console. Lets expose the ports in different ways.
4.7.1. Default Port Mapping
The following command will override the default command in Docker file, start WildFly, and bind application and management port to all network interfaces.
#From Internet
docker run --name managed-wildfly -P -d jboss/wildfly /opt/jboss/wildfly/bin/standalone.sh -b 0.0.0.0 -bmanagement 0.0.0.0
#From Instructor
docker run --name managed-wildfly -P -d classroom.example.com:5000/wildfly /opt/jboss/wildfly/bin/standalone.sh -b 0.0.0.0 -bmanagement 0.0.0.0
Accessing WildFly Administration Console require a user in administration realm. A pre-created image, with appropriate username/password credentials, is used to start WildFly as:
#From Internet
docker run --name managed-wildfly-from-image -P -d rafabene/wildfly-admin
#From Instructor
docker run --name managed-wildfly-from-image -P -d classroom.example.com:5000/wildfly-management
-P map any exposed ports inside the image to a random port on Docker host.
Look at the exposed ports as:
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
5fdedef5573b rafabene/wildfly-admin "/bin/sh -c '/opt/jb 15 seconds ago Up 15 seconds 0.0.0.0:32772->8080/tcp, 0.0.0.0:32771->9990/tcp managed-wildfly-from-image
ee30433b5414 jboss/wildfly "/opt/jboss/wildfly/ 59 seconds ago Up 59 seconds 0.0.0.0:32769->8080/tcp managed-wildfly
Look for the host port that is mapped in the container, 32769 in this case. Access the admin console at http://dockerhost:32769.
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Note
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Exact port number may be different in your case. |
The username/password credentials are:
| Field | Value |
|---|---|
Username |
admin |
Password |
docker#admin |
This shows the admin console as:
Additional Ways To Find Port Mapping
The exact mapped port can also be found as:
-
Using
docker port:docker port managed-wildfly-from-imageto see the output as:
0.0.0.0:32769->8080/tcp 0.0.0.0:32770->9990/tcp -
Using
docker inspect:docker inspect --format='{{(index (index .NetworkSettings.Ports "9990/tcp") 0).HostPort}}' managed-wildfly-from-image
4.7.2. Fixed Port Mapping
This management image can also be started with a pre-defined port mapping as:
#From Internet
docker run -p 8080:8080 -p 9990:9990 -d rafabene/wildfly-admin
#From Instructor
docker run -p 8080:8080 -p 9990:9990 -d classroom.example.com:5000/wildfly-management
In this case, Docker port mapping will be shown as:
8080/tcp -> 0.0.0.0:8080
9990/tcp -> 0.0.0.0:9990
5. Build an Image
PURPOSE: This chapter explains how to create a Docker image.
As explained in Docker Basics, Docker image is the build component of Docker and a read-only template of application operating system.
5.1. Dockerfile
Docker build images by reading instructions from a Dockerfile. A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. docker build command uses this file and executes all the commands in succession to create an image.
build command is also passed a context that is used during image creation. This context can be a path on your local filesystem or a URL to a Git repository.
Dockerfile is usually called Dockerfile. The complete list of commands that can be specified in this file are explained at https://docs.docker.com/reference/builder/. The common commands are listed below:
| Command | Purpose | Example |
|---|---|---|
FROM |
First non-comment instruction in Dockerfile |
|
COPY |
Copies mulitple source files from the context to the file system of the container at the specified path |
|
ENV |
Sets the environment variable |
|
RUN |
Executes a command |
|
CMD |
Defaults for an executing container |
|
EXPOSE |
Informs the network ports that the container will listen on |
|
5.2. Create your first Docker image
-
Create a new directory.
-
Create a new text file, name it Dockerfile, and use the following contents:
#From Internet (use only one FROM instruction)
FROM fedora
#From Instructor (use only one FROM instruction)
FROM classroom.example.com:5000/fedora
CMD ["/bin/echo", "hello world"]
This image uses fedora as the base image. CMD command defines the command that needs to run. It provides a different entry point of /bin/echo and gives the argument “hello world”.
-
Build this image:
> docker build -t helloworld .
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM fedora
latest: Pulling from library/fedora
369aca82a5c0: Pull complete
a887c7ad7f3f: Pull complete
Digest: sha256:a220110e096cd1d6034699a5e30a012de6c55c83149d01658120918d01f1587a
Status: Downloaded newer image for fedora:latest
---> a887c7ad7f3f
Step 2 : CMD /bin/echo hello world
---> Running in 47e65a18749c
---> 405849ed68f1
Removing intermediate container 47e65a18749c
Successfully built 405849ed68f1
. in this command is the context for docker build.
-
List the images available:
> docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
helloworld latest 405849ed68f1 18 seconds ago 204.3 MB
fedora latest a887c7ad7f3f 6 days ago 204.3 MB
-
Run the container:
docker run -it helloworld
to see the output:
hello world
-
Change the base image from
fedoratobusyboxinDockerfile. Build the image again:docker build -t helloworld2 .
and view the images as:
> docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
helloworld2 latest 3dece940fa4a 6 seconds ago 1.109 MB
helloworld latest 405849ed68f1 About a minute ago 204.3 MB
fedora latest a887c7ad7f3f 6 days ago 204.3 MB
busybox latest c51f86c28340 8 days ago 1.109 MB
5.3. WildFly Image
-
Create a new directory.
-
Create a new text file, name it Dockerfile, and use the following contents:
#From Internet (use only one FROM instruction)
FROM jboss/wildfly
#From Instructor (use only one FROM instruction)
FROM classroom.example.com:5000/wildfly
-
Build the image:
docker build -t mywildfly .
-
Run the container:
docker run -it mywildfly
5.4. Import and export images
Docker images can be saved using save command to a .tar file:
docker save helloworld > helloworld.tar
These tar files can then be imported using load command:
docker load -i helloworld.tar
6. Deploy Java EE 7 Application (Pre-Built WAR)
Java EE 7 Movieplex is a standard multi-tier enterprise application that shows design patterns and anti-patterns for a typical Java EE 7 application.
Pull the Docker image that contains WildFly and pre-built Java EE 7 application WAR file as shown:
#From Internet
docker pull arungupta/javaee7-hol
#From Instructor
docker pull classroom.example.com:5000/javaee7-hol
The javaee7-hol Dockerfile is based on jboss/wildfly and adds the movieplex7 application as war file.
Run it:
#From Internet
docker run -it -p 8080:8080 arungupta/javaee7-hol
#From Instructor
docker run -it -p 8080:8080 classroom.example.com:5000/javaee7-hol
See the application in action at http://dockerhost:8080/movieplex7/. The output is shown:
|
Note
|
It might take a while for the container to come up. Wait for the server to complete the startup. |
This uses an in-memory database with WildFly application server as shown in the image:
Only two changes are required to the standard jboss/wildfly image:
-
By default, WildFly starts in Web platform. This Java EE 7 application uses some capabilities from the Full Platform and so WildFly is started in that mode instead as:
CMD ["/opt/jboss/wildfly/bin/standalone.sh", "-c", "standalone-full.xml", "-b", "0.0.0.0"] -
WAR file is copied to the
standalone/deploymentsdirectory as:RUN curl -L https://github.com/javaee-samples/javaee7-hol/raw/master/solution/movieplex7-1.0-SNAPSHOT.war -o /opt/jboss/wildfly/standalone/deployments/movieplex7-1.0-SNAPSHOT.war
7. Deploy Java EE 7 Application (Container Linking)
Deploy Java EE 7 Application (Pre-Built WAR) explained how to use an in-memory database with the application server. This gets you started rather quickly but becomes a bottleneck soon as the database is only in-memory. This means that any changes made to your schema and data are lost when the application server shuts down. In this case, you need to use a database server that resides outside the application server. For example, MySQL as the database server and WildFly as the application server.
This section will show how Docker Container Linking can be used to connect to a service running inside a Docker container via a network port.
-
Start MySQL server as:
#From Internet docker run --name mysqldb -e MYSQL_USER=mysql -e MYSQL_PASSWORD=mysql -e MYSQL_DATABASE=sample -e MYSQL_ROOT_PASSWORD=supersecret -p 3306:3306 -d mysql #From Instructor docker run --name mysqldb -e MYSQL_USER=mysql -e MYSQL_PASSWORD=mysql -e MYSQL_DATABASE=sample -e MYSQL_ROOT_PASSWORD=supersecret -p 3306:3306 -d classroom.example.com:5000/mysql-edefine environment variables that are read by the database at startup and allow us to access the database with this user and password. -
Start WildFly with the deployed Java EE 7 application as:
#From Internet docker run -d --name mywildfly-mysql --link mysqldb:db -p 8080:8080 arungupta/wildfly-mysql-javaee7 #From Instructor docker run -d --name mywildfly-mysql --link mysqldb:db -p 8080:8080 classroom.example.com:5000/wildfly-mysql-javaee7--linktakes two parameters - first is name of the container we’re linking to and second is the alias for the link name.NoteContainer LinkingCreating a link between two containers creates a conduit between a source container and a target container and securely transfer information about source container to target container.
In our case, target container (WildFly) can see information about source container (MySQL). When containers are linked, information about a source container can be sent to a recipient container. This allows the recipient to see selected data describing aspects of the source container. For example, IP address of MySQL server is expoed at $DB_PORT_3306_TCP_ADDR and port of MySQL server is exposed at $DB_PORT_3306_TCP_PORT. These are then used to create the JDBC resource.
See more about container communication on the Docker website Linking Containers Together
-
See the output as:
> curl http://dockerhost:8080/employees/resources/employees <?xml version="1.0" encoding="UTF-8" standalone="yes"?><collection><employee><id>1</id><name>Penny</name></employee><employee><id>2</id><name>Sheldon</name></employee><employee><id>3</id><name>Amy</name></employee><employee><id>4</id><name>Leonard</name></employee><employee><id>5</id><name>Bernadette</name></employee><employee><id>6</id><name>Raj</name></employee><employee><id>7</id><name>Howard</name></employee><employee><id>8</id><name>Priya</name></employee></collection>
|
Note
|
If you get a 404 or any other error, wait for a little longer until the containers are started up. |
Lets stop the previously running container as:
docker stop mywildfly-mysql
8. Build and Deploy Java EE 7 Application
Now that you learned a lot about images, containers and how to link them together, it is about time to learn about the different deployment options. Let’s start over with the Java EE 7 sample applications again. Java EE 7 Simple Sample is a trivial Java EE 7 sample application and a perfect way to start.
8.1. Build Application
We’re going to build the application first.
-
Clone the repo:
#From Internet git clone https://github.com/javaee-samples/javaee7-simple-sample.git
#From Instructor git clone http://root:dockeradmin@classroom.example.com:10080/root/javaee7-simple-sample.git
-
Build the application:
cd javaee7-simple-sample/
#From Internet
mvn clean package
#From Instructor
curl http://classroom.example.com:8082/downloads/lab-settings.xml -o settings.xml
mvn -s settings.xml clean package
8.2. Start Application Server
Create a folder to place the deployments and give it write access
mkdir deployments
chmod a+w deployments
Start WildFly server as:
#From Internet
docker run --name wildfly -d -p 8080:8080 -v `pwd`/deployments:/opt/jboss/wildfly/standalone/deployments/:rw jboss/wildfly
#From Instructor
docker run --name wildfly -d -p 8080:8080 -v `pwd`/deployments:/opt/jboss/wildfly/standalone/deployments/:rw classroom.example.com:5000/wildfly
|
Note
|
Windows users need to tweak this a bit and copy the deployments to c:/Users/<USER>/deployments because the directory mappings for boot2docker work differently on those systems. Please update the docker -v argument accordingly. 'docker run --name wildfly -d -p 8080:8080 -v /c/Users/meisele/deployments:/opt/jboss/wildfly/standalone/deployments/:rw [classroom.example.com:5000|jboss]/wildfly' |
This command starts a container named “wildfly”.
The -v flag maps a directory from the host into the container. This will be the directory to put the deployments. rw ensures that the Docker container can write to it.
Check logs to verify if the server has started.
docker logs -f wildfly
Access http://dockerhost:8080 in your browser to make sure the instance is up and running.
Now you’re ready to deploy the application for the first time.
8.3. Configure JBoss Developer Studio
Start JBoss Developer Studio, if not already started.
-
Select ‘Servers’ tab, create a new server adapter
-
Assign an existing or create a new WildFly 9.0.0 runtime (changed properties are highlighted.)
-
If a new runtime needs to be created, pick the directory for WildFly 9.0.2:
Click on ‘Finish’.
-
Double-click on the newly selected server to configure server properties:
The host name is specified to ‘dockerhost’. Two properties on the left are automatically propagated from the previous dialog. Additional two properties on the right side are required to disable to keep deployment scanners in sync with the server.
-
Specify a custom deployment folder on Deployment tab of Server Editor
-
Right-click on the newly created server adapter and click ‘Start’.
8.4. Deploy Application Using Shared Volumes
-
Import javaee7-simple-sample application source code using Import → Existing Maven Projects.
-
Right-click on the project, select ‘Run on Server’ and chose the previously created server.
The project runs and displays the start page of the application.
Congratulations!
You’ve deployed your first application to WildFly running in a Docker container from JBoss Developer Studio.
Stop WildFly container when you’re done.
docker stop wildfly
8.5. Deploy Application Using CLI
TThe Command Line Interface (CLI) is a tool for connecting to WildFly instances to manage all tasks from command line environment. Some of the tasks that you can do using the CLI are:
-
Deploy/Undeploy web application in standalone/Domain Mode.
-
View all information about the deployed application on runtime.
-
Start/Stop/Restart Nodes in respective mode i.e. Standalone/Domain.
-
Adding/Deleting resource or subsystems to servers.
Lets use the CLI to deploy javaee7-simple-sample to WildFly running in the container.
-
CLI needs to be locally installed and comes as part of WildFly. This should be available in the previously downloaded WildFly. Unzip into a folder of your choice (e.g.
/Users/<USER>/tools/). This will createwildfly-9.0.2.Finaldirectory here. This folder is referred to $WIDLFY_HOME from here on. Make sure to add the/Users/<USER>/tools/wildfly-9.0.2.Final/binto your $PATH. -
Run the “wildfly-management” image with fixed port mapping as explained in Fixed Port Mapping.
-
Run the
jboss-clicommand and connect to the WildFly instance.
Start WildFly server as:
#From Internet
docker run --name wildfly-managed -d -p 8080:8080 -p 9990:9990 rafabene/wildfly-admin
#From Instructor
docker run --name wildfly-managed -d -p 8080:8080 -p 9990:9990 classroom.example.com:5000/wildfly-management
This command starts a container named “wildfly-managed”.
jboss-cli.sh --controller=dockerhost:9990 -u=admin -p=docker#admin -c
This will show the output as:
[standalone@dockerhost:9990 /]
-
Deploy the application as:
deploy <javaee7-simple-sample PATH>target/javaee7-simple-sample-1.10.war --force
Now you’ve sucessfully used the CLI to remote deploy the Java EE 7 sample application to WildFly running as docker container.
8.6. Deploy Application Using Web Console
WildFly comes with a web-based administration console. It also relies on the same management APIs that are used by JBoss Developer Tools and the CLI. It provides a simple and easy to use web-based console to manage WildFly instance. For a Docker image, it needs to be explicitly enabled as explained in Enabling WildFly Administration. Once enabled, it can be accessed at http://dockerhost:9990.
Username and password credentials are shown in [WildFly_Administration_Credentials].
|
Note
|
You may like to stop and remove the Docker container running WildFly. This can be done as Start a new container as |
Deploy the application using the console with the following steps:
-
Go to ‘Deployments’ tab.
-
Click on ‘Add’ button.
-
On ‘Add Deployment’ screen, take the default of ‘Upload a new deployment’ and click ‘Next>>’.
-
Click on ‘Choose File’, select
<javaee7-simple-sample PATH>/javaee7-simple-sample.warfile on your computer. This would bejavaee7-simple-sample/target/javaee7-simple-sample.warfrom Build Application. -
Click on ‘Next>>’.
-
Select ‘Enable’ checkbox.
-
Click ‘Finish’.
This will complete the deployment of the Java EE 7 application using Web Console. The output can be seen out http://dockerhost:8080/javaee7-simple-sample and looks like:
8.7. Deploy Application Using Management API
A standalone WildFly process, process can be configured to listen for remote management requests using its “native management interface”. The CLI tool that comes with the application server uses this interface, and user can develop custom clients that use it as well. By default, WildFly management interface listens on 127.0.0.1. When running inside a Docker container, the network interface should be bound to all publicly assigned addresses. This can be easily changed by biding to 0.0.0.0 instead of 127.0.0.1.
-
Start another WildFly instance again:
#From Internet
docker run -d --name wildfly -p 8080:8080 -p 9990:9990 rafabene/wildfly-admin
#From Instructor
docker run -d --name wildfly -p 8080:8080 -p 9990:9990 classroom.example.com:5000/wildfly-management
In addition to application port 8080, the administration port 9990 is exposed as well. The WildFly image that is used has tweaked the start script such that the management interface is bound to 0.0.0.0.
-
Create a new server adapter in JBoss Developer Studio and name it “WildFly 9.0.2-Management”. Specify the host name as ‘dockerhost’.
-
Click on ‘Next>’ and change the values as shown.
-
Take the default values in ‘Remote System Integration’ and click on ‘Finish’.
-
Change server properties by double clicking on the newly created server adapter. Specify admin credentials (username: docker, password: docker#admin). Note, you need to delete the existing password and use this instead:
-
Right-click on the newly created server adapter and click ‘Start’. Status quickly changes to ‘Started’ as shown.
-
Right-click on the javaee7-simple-sample project, select ‘Run on Server’ and choose this server. The project runs and displays the start page of the application.
-
Stop WildFly when you’re done.
docker stop wildfly
9. Multiple Containers Using Docker Compose
Docker Compose is a tool for defining and running complex applications with Docker. With Compose, you define a multi-container application in a single file, then spin your application up in a single command which does everything that needs to be done to get it running.
An application using Docker containers will typically consist of multiple containers. With Docker Compose, there is no need to write shell scripts to start your containers. All the containers are defined in a configuration file using services, and then docker-compose script is used to start, stop, and restart the application and all the services in that application, and all the containers within that service. The complete list of commands is:
| Command | Purpose |
|---|---|
|
Build or rebuild services |
|
Get help on a command |
|
Kill containers |
|
View output from containers |
|
Print the public port for a port binding |
|
List containers |
|
Pulls service images |
|
Restart services |
|
Remove stopped containers |
|
Run a one-off command |
|
Set number of containers for a service |
|
Start services |
|
Stop services |
|
Create and start containers |
|
Note
|
According to https://docs.docker.com/compose/install/ "You can run Compose on OS X and 64-bit Linux. It is currently not supported on the Windows operating system." |
9.1. Install docker compose (For Linux users)
sudo curl -L https://github.com/docker/compose/releases/download/1.5.0/docker-compose-`uname -s`-`uname -m` -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose
9.2. Configuration File
-
Entry point to Compose is
docker-compose.yml. Lets use the following file:mysqldb: #From Internet (use only one image instruction) image: mysql #From Instructor (use only one image instruction) image: classroom.example.com:5000/mysql environment: MYSQL_DATABASE: sample MYSQL_USER: mysql MYSQL_PASSWORD: mysql MYSQL_ROOT_PASSWORD: supersecret mywildfly: #From Internet (use only one image instruction) image: arungupta/wildfly-mysql-javaee7 #From Instructor (use only one image instruction) image: classroom.example.com:5000/wildfly-mysql-javaee7 links: - mysqldb:db ports: - 8080This file is available in https://raw.githubusercontent.com/redhat-developer/docker-java/devoxxma2015/attendees/ and shows:
-
Two services defined by the name
mysqldbandmywildfly -
Image name for each service defined using
image -
Environment variables for the MySQL container are defined in
environment -
MySQL container is linked with WildFly container using
links -
Port forwarding is achieved using
ports
-
9.3. Start Services
-
Save the
docker-compose-internet.ymlasdocker-compose.ymlif you are running from Internet or -
Save the
docker-compose-instructor.ymlasdocker-compose.ymlif you are using images from Instructor. -
All services can be started, in detached mode, by giving the command:
docker-compose up -d
And this shows the output as:
Creating attendees_mysqldb_1... Creating attendees_mywildfly_1...
An alternate compose file name can be specified using
-f.An alternate directory where the compose file exists can be specified using
-p. -
Started services can be verified as:
> docker-compose ps Name Command State Ports ------------------------------------------------------------------------------------------------- attendees_mysqldb_1 /entrypoint.sh mysqld Up 3306/tcp attendees_mywildfly_1 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32773->8080/tcpThis provides a consolidated view of all the services started, and containers within them.
Alternatively, the containers in this application, and any additional containers running on this Docker host can be verified by using the usual
docker pscommand:> docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 3598e545bd2f arungupta/wildfly-mysql-javaee7:latest "/opt/jboss/wildfly/ 59 seconds ago Up 58 seconds 0.0.0.0:32773->8080/tcp attendees_mywildfly_1 b8cf6a3d518b mysql:latest "/entrypoint.sh mysq 2 minutes ago Up 2 minutes 3306/tcp attendees_mysqldb_1 -
Service logs can be seen as:
> docker-compose logs Attaching to attendees_mywildfly_1, attendees_mysqldb_1 mywildfly_1 | => Starting WildFly server mywildfly_1 | => Waiting for the server to boot mywildfly_1 | ========================================================================= mywildfly_1 | mywildfly_1 | JBoss Bootstrap Environment mywildfly_1 | mywildfly_1 | JBOSS_HOME: /opt/jboss/wildfly mywildfly_1 | mywildfly_1 | JAVA: /usr/lib/jvm/java/bin/java mywildfly_1 | mywildfly_1 | JAVA_OPTS: -server -Xms64m -Xmx512m -XX:MaxPermSize=256m -Djava.net.preferIPv4Stack=true -Djboss.modules.system.pkgs=org.jboss.byteman -Djava.awt.headless=true mywildfly_1 | . . . mywildfly_1 | 15:40:20,866 INFO [org.jboss.resteasy.spi.ResteasyDeployment] (MSC service thread 1-2) Deploying javax.ws.rs.core.Application: class org.javaee7.samples.employees.MyApplication mywildfly_1 | 15:40:20,914 INFO [org.wildfly.extension.undertow] (MSC service thread 1-2) JBAS017534: Registered web context: /employees mywildfly_1 | 15:40:21,032 INFO [org.jboss.as.server] (ServerService Thread Pool -- 28) JBAS018559: Deployed "employees.war" (runtime-name : "employees.war") mywildfly_1 | 15:40:21,077 INFO [org.jboss.as] (Controller Boot Thread) JBAS015961: Http management interface listening on http://127.0.0.1:9990/management mywildfly_1 | 15:40:21,077 INFO [org.jboss.as] (Controller Boot Thread) JBAS015951: Admin console listening on http://127.0.0.1:9990 mywildfly_1 | 15:40:21,077 INFO [org.jboss.as] (Controller Boot Thread) JBAS015874: WildFly 8.2.0.Final "Tweek" started in 9572ms - Started 280 of 334 services (92 services are lazy, passive or on-demand) mysqldb_1 | Running mysql_install_db mysqldb_1 | 2015-06-05 15:38:31 0 [Note] /usr/sbin/mysqld (mysqld 5.6.25) starting as process 27 ... mysqldb_1 | 2015-06-05 15:38:31 27 [Note] InnoDB: Using atomics to ref count buffer pool pages . . . mysqldb_1 | 2015-06-05 15:38:40 1 [Note] Event Scheduler: Loaded 0 events mysqldb_1 | 2015-06-05 15:38:40 1 [Note] mysqld: ready for connections. mysqldb_1 | Version: '5.6.25' socket: '/var/run/mysqld/mysqld.sock' port: 3306 MySQL Community Server (GPL) mysqldb_1 | 2015-06-05 15:40:18 1 [Warning] IP address '172.17.0.24' could not be resolved: Name or service not known
9.4. Verify Application
-
Access the application at http://dockerhost:32773/employees/resources/employees/. This is shown in the browser as:
|
Note
|
Use the port displayed in the docker-compose ps command.
|
9.5. Scale Services
TODO Improve the explanation
You can scale the services up as:
docker-compose scale mywildfly=4 Creating and starting 2... done Creating and starting 3... done Creating and starting 4... done
Check the logs…
docker-compose logs
Check the running instances:
docker-compose ps
Name Command State Ports
-------------------------------------------------------------------------------------
rafael_mysqldb_1 /entrypoint.sh mysqld Up 3306/tcp
rafael_mywildfly_1 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32773->8080/tcp
rafael_mywildfly_2 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32777->8080/tcp
rafael_mywildfly_3 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32780->8080/tcp
rafael_mywildfly_4 /opt/jboss/wildfly/customi ... Up 0.0.0.0:32781->8080/tcp
You can also decide to reduce the number of running instances:
docker-compose scale mywildfly=2 Stopping rafael_mywildfly_3... done Stopping rafael_mywildfly_4... done Removing rafael_mywildfly_3... done Removing rafael_mywildfly_4... done
9.6. Stop Services
Stop the services as:
docker-compose stop Stopping attendees_mywildfly_1... Stopping attendees_mywildfly_2... Stopping attendees_mysqldb_1...
|
Warning
|
Stopping and starting the containers again will give the following error:
This is expected because the JDBC resource is created during every run of the container. In a real-world application, this would be pre-baked in the configuration already. |
9.7. Remove Containers
Stop the services as:
docker-compose rm Going to remove rafael_mywildfly_4, rafael_mywildfly_3, rafael_mywildfly_2, rafael_mywildfly_1, rafael_mysqldb_1 Are you sure? [yN] y Removing rafael_mywildfly_2... done Removing rafael_mywildfly_1... done Removing rafael_mysqldb_1... done
10. Deploy Application on Kubernetes Cluster
10.1. Install Kubernetes
-
Download Vagrant and install it.
-
from Internet: https://www.vagrantup.com/downloads.html
-
from Instructor: http://classroom.example.com:8082/downloads/vagrant/
Kubernetes requires Vagrant >= 1.6.2. So if you have an older version then make sure you install the latest one.
-
-
If you’ve not installed Docker Toolbox, then you need to additionally download Virtual Box 5.0.8
-
from Internet: https://www.virtualbox.org/wiki/Downloads.
-
from Instructor: http://classroom.example.com:8082/downloads/virtualbox/
-
-
Download Kubernetes (1.0.7)
Kubernetes is an open source system for managing containerized applications across multiple hosts, providing basic mechanisms for deployment, maintenance, and scaling of applications.
Kubernetes, or “k8s” in short, allows the user to provide declarative primitives for the desired state, for example “need 5 WildFly servers and 1 MySQL server running”. Kubernetes self-healing mechanisms, such as auto-restarting, re-scheduling, and replicating containers then ensure that this state is met. The user just define the state and Kubernetes ensures that the state is met at all times on the cluster.
How is it related to Docker?
Docker provides the lifecycle management of containers. A Docker image defines a build time representation of the runtime containers. There are commands to start, stop, restart, link, and perform other lifecycle methods on these containers. Kubernetes uses Docker to package, instantiate, and run containerized applications.
How does Kubernetes simplify containerized application deployment?
A typical application would have a cluster of containers across multiple hosts. For example, your web tier (for example Undertow) might run as a few instances, and likely on a set of containers. Similarly, your application tier (for example, WildFly) would run on a different set of containers. The web tier would need to delegate the request to application tier. The web, application, and database tier would generally run on a separate set of containers. These containers would need to talk to each other. Using any of the solutions mentioned above would require scripting to start the containers, and monitoring/bouncing if something goes down. Kubernetes does all of that for the user after the application state has been defined.
10.2. Key Components
At a very high level, there are three key components:
-
Pods are the smallest deployable units that can be created, scheduled, and managed. Its a logical collection of containers that belong to an application.
-
Master is the central control point that provides a unified view of the cluster. There is a single master node that control multiple worker nodes.
-
Node (née minion) is a worker node that run tasks as delegated by the master. Nodes can run one or more pods. It provides an application-specific “virtual host” in a containerized environment.
A picture is always worth a thousand words and so this is a high-level logical block diagram for Kubernetes:
After the 50,000 feet view, lets fly a little lower at 30,000 feet and take a look at how Kubernetes make all of this happen. There are a few key components at Master and Node that make this happen.
-
Replication Controller is a resource at Master that ensures that requested number of pods are running on nodes at all times.
-
Service is an object on master that provides load balancing across a replicated group of pods. Label is an arbitrary key/value pair in a distributed watchable storage that the Replication Controller uses for service discovery.
-
Kubelet Each node runs services to run containers and be managed from the master. In addition to Docker, Kubelet is another key service installed there. It reads container manifests as YAML files that describes a pod. Kubelet ensures that the containers defined in the pods are started and continue running.
-
Master serves RESTful Kubernetes API that validate and configure Pod, Service, and Replication Controller.
10.3. Start Kubernetes Cluster
Kubernetes cluster can be easily started using Vagrant. There are two options to start the cluster - first using a downloaded Kubernetes distribution bundle and second by downloading the latest bundle as part of the install.
10.3.1. Using Previously Downloaded Kubernetes Distribution
-
Setup a Kubernetes cluster as:
cd kubernetes
export NUM_MINIONS=2
export KUBERNETES_PROVIDER=vagrant
./cluster/kube-up.sh
The KUBERNETES_PROVIDER environment variable tells all of the various cluster management scripts which variant to use.
The `NUM_MINIONS`environment variable controls the number of nodes that are instantiated
|
Note
|
This will take a few minutes, so be patience! Vagrant will provision each machine in the cluster with all the necessary components to run Kubernetes. |
It shows the output as:
Starting cluster using provider: vagrant
... calling verify-prereqs
... calling kube-up
Using credentials: vagrant:vagrant
. . .
Validate output:
NAME STATUS MESSAGE ERROR
controller-manager Healthy ok nil
scheduler Healthy ok nil
etcd-0 Healthy {"health": "true"} nil
Cluster validation succeeded
Done, listing cluster services:
Kubernetes master is running at https://10.245.1.2
KubeDNS is running at https://10.245.1.2/api/v1/proxy/namespaces/kube-system/services/kube-dns
KubeUI is running at https://10.245.1.2/api/v1/proxy/namespaces/kube-system/services/kube-ui
Note down the address for Kubernetes master, https://10.245.1.2 in this case.
10.3.2. Download and Start the Kubernetes Cluster
-
Alternatively, the cluster can also be started as:
> curl -sS https://get.k8s.io | bash Downloading kubernetes release v0.21.1 to /Users/arungupta/tools/kubernetes.tar.gz --2015-07-13 15:56:54-- https://storage.googleapis.com/kubernetes-release/release/v0.21.1/kubernetes.tar.gz Resolving storage.googleapis.com... 74.125.28.128, 2607:f8b0:400e:c02::80 Connecting to storage.googleapis.com|74.125.28.128|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 117901998 (112M) [application/x-tar] Saving to: 'kubernetes.tar.gz' kubernetes.tar.gz 100%[=========================================================>] 112.44M 6.21MB/s in 18s 2015-07-13 15:57:13 (6.13 MB/s) - 'kubernetes.tar.gz' saved [117901998/117901998] . . . NAME STATUS MESSAGE ERROR controller-manager Healthy ok nil scheduler Healthy ok nil etcd-0 Healthy {"health": "true"} nil Cluster validation succeeded Done, listing cluster services: Kubernetes master is running at https://10.245.1.2 KubeDNS is running at https://10.245.1.2/api/v1/proxy/namespaces/kube-system/services/kube-dns KubeUI is running at https://10.245.1.2/api/v1/proxy/namespaces/kube-system/services/kube-ui Kubernetes binaries at /Users/arungupta/tools/kubernetes/kubernetes/cluster/ You may want to add this directory to your PATH in $HOME/.profile Installation successful!
10.3.3. Verify the Cluster
-
Verify the Kubernetes cluster as:
kubernetes> vagrant status
Current machine states:
master running (virtualbox)
minion-1 running (virtualbox)
This environment represents multiple VMs. The VMs are all listed
above with their current state. For more information about a specific
VM, run `vagrant status NAME`.
By default, the Vagrant setup will create a single Master and one node. Each VM will take 1 GB, so make sure you have at least 2GB to 4GB of free memory (plus appropriate free disk space).
|
Note
|
By default, only one node is created. This can be manipulated by setting an environment variable NUM_MINIONS variable to an integer before invoking kube-up.sh script.
|
By default, each VM in the cluster is running Fedora, Kubelet is installed into ``systemd'', and all other Kubernetes services are running as containers on Master.
-
Access https://10.245.1.2 (or whatever IP address is assigned to your kubernetes cluster start up log). This may present the warning as shown below:
Click on ‘Advanced’, on ‘Proceed to 10.245.1.2’, enter the username as ‘vagrant’ and password as ‘vagrant’ to see the output as:
Check the list of nodes as:
> ./cluster/kubectl.sh get nodes
NAME LABELS STATUS
10.245.1.3 kubernetes.io/hostname=10.245.1.3 Ready
-
Check the list of pods:
kubernetes> ./cluster/kubectl.sh get po
NAME READY STATUS RESTARTS AGE
-
Check the list of services running:
kubernetes> ./cluster/kubectl.sh get se
NAME LABELS SELECTOR IP(S) PORT(S)
kubernetes component=apiserver,provider=kubernetes <none> 10.247.0.1 443/TCP
-
Check the list of replication controllers:
kubernetes> ./cluster/kubectl.sh get rc
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
10.4. Deploy Java EE Application (multiple configuration files)
Pods, and the IP addresses assigned to them, are ephemeral. If a pod dies then Kubernetes will recreate that pod because of its self-healing features, but it might recreate it on a different host. Even if it is on the same host, a different IP address could be assigned to it. And so any application cannot rely upon the IP address of the pod.
Kubernetes services is an abstraction which defines a logical set of pods. A service is typically back-ended by one or more physical pods (associated using labels), and it has a permanent IP address that can be used by other pods/applications. For example, WildFly pod can not directly connect to a MySQL pod but can connect to MySQL service. In essence, Kubernetes service offers clients an IP and port pair which, when accessed, redirects to the appropriate backends.
|
Note
|
In this case, all the pods are running on a single node. This is because, that is the default number for a Kubernetes cluster. The pod can be on another node if more number of nodes are configured to start in the cluster. |
Any Service that a Pod wants to access must be created before the Pod itself, or else the environment variables will not be populated.
The order of Service and the targeted Pods does not matter. However Service needs to be started before any other Pods consuming the Service are started.
10.4.1. Start MySQL Pod
-
Start MySQL Pod:
./cluster/kubectl.sh create -f ../../attendees/kubernetes/app-mysql-pod.yaml
pods/mysql-pod
It uses the following configuration file:
apiVersion: v1
kind: Pod
metadata:
name: mysql-pod
labels:
name: mysql-pod
context: docker-k8s-lab
spec:
containers:
-
name: mysql
image: mysql:latest
env:
-
name: "MYSQL_USER"
value: "mysql"
-
name: "MYSQL_PASSWORD"
value: "mysql"
-
name: "MYSQL_DATABASE"
value: "sample"
-
name: "MYSQL_ROOT_PASSWORD"
value: "supersecret"
ports:
-
containerPort: 3306
-
Get status of the Pod:
kubernetes> ./cluster/kubectl.sh get -w po
NAME READY STATUS RESTARTS AGE
mysql-pod 0/1 Pending 0 4s
NAME READY STATUS RESTARTS AGE
mysql-pod 0/1 Running 0 44s
mysql-pod 1/1 Running 0 44s
-w watches for changes to the requested object. Wait for the MySQL pod to be in Running status.
10.4.2. Start MySQL service
-
Start MySQL Service:
./cluster/kubectl.sh create -f ../../attendees/kubernetes/app-mysql-service.yaml
services/mysql-service
It uses the following configuration file:
apiVersion: v1
kind: Service
metadata:
name: mysql-service
labels:
name: mysql-pod
context: docker-k8s-lab
spec:
ports:
# the port that this service should serve on
- port: 3306
# label keys and values that must match in order to receive traffic for this service
selector:
name: mysql-pod
context: docker-k8s-lab
Once again, the label “context: docker-k8s-lab” is used. This simplifies querying the created pods later on.
-
Get status of the Service:
./cluster/kubectl.sh get -w se
NAME LABELS SELECTOR IP(S) PORT(S)
kubernetes component=apiserver,provider=kubernetes <none> 10.247.0.1 443/TCP
mysql-service context=docker-k8s-lab,name=mysql-pod context=docker-k8s-lab,name=mysql-pod 10.247.63.43 3306/TCP
If multiple services are running, then it can be narrowed by specifying the labels:
./cluster/kubectl.sh get -w po -l context=docker-k8s-lab,name=mysql-pod
NAME READY STATUS RESTARTS AGE
mysql-pod 1/1 Running 0 4m
This is also the selector label used by Service to target Pods.
When a Service is run on a node, the kubelet adds a set of environment variables for each active Service. It supports both Docker links compatible variables and simpler {SVCNAME}_SERVICE_HOST and {SVCNAME}_SERVICE_PORT variables, where the Service name is upper-cased and dashes are converted to underscores.
Our service name is “mysql-service” and so MYSQL_SERVICE_SERVICE_HOST and MYSQL_SERVICE_SERVICE_PORT variables are available to other pods.
Kubernetes also allows services to be resolved using DNS configuration. Send a Pull Request for adding this functionality to the lab as explained in #62.
10.4.3. Start WildFly Replication Controller
-
Start WildFly replication controller:
./cluster/kubectl.sh create -f ../../attendees/kubernetes/app-wildfly-rc.yaml
replicationcontrollers/wildfly-rc
It uses the following configuration file:
apiVersion: v1
kind: ReplicationController
metadata:
name: wildfly-rc
labels:
name: wildfly
context: docker-k8s-lab
spec:
replicas: 1
template:
metadata:
labels:
name: wildfly
spec:
containers:
- name: wildfly-rc-pod
image: arungupta/wildfly-mysql-javaee7:k8s
ports:
- containerPort: 8080
-
Check status of the Pod inside Replication Controller:
./cluster/kubectl.sh get po
NAME READY STATUS RESTARTS AGE
mysql-pod 1/1 Running 0 1h
wildfly-rc-w2kk5 1/1 Running 0 6m
-
Get IP address of the Pod:
./cluster/kubectl.sh get -o template po wildfly-rc-w2kk5 --template={{.status.podIP}}
10.246.1.23
10.4.4. Access the application (from inside a node)
-
Log in to node:
vagrant ssh minion-1
-
Access the application using
curl http://10.246.1.23:8080/employees/resources/employees/and replace IP address with the one obtained earlier:
Last login: Thu Jul 16 00:24:36 2015 from 10.0.2.2
[vagrant@kubernetes-minion-1 ~]$ curl http://10.246.1.23:8080/employees/resources/employees/
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><collection><employee><id>1</id><name>Penny</name></employee><employee><id>2</id><name>Sheldon</name></employee><employee><id>3</id><name>Amy</name></employee><employee><id>4</id><name>Leonard</name></employee><employee><id>5</id><name>Bernadette</name></employee><employee><id>6</id><name>Raj</name></employee><employee><id>7</id><name>Howard</name></employee><employee><id>8</id><name>Priya</name></employee></collection>
10.4.5. Access the application (using Services)
For some parts of your application (e.g. frontends) you may want to expose a Service onto an external (outside of your cluster, maybe public internet) IP address, other services should be visible only from inside of the cluster.
Kubernetes ServiceTypes allow you to specify what kind of service you want. The default and base type is ClusterIP, which exposes a service to connection from inside the cluster. NodePort and LoadBalancer are two types that expose services to external traffic.
Valid values for the ServiceType field are:
-
ClusterIP: use a cluster-internal IP only - this is the default and is discussed above. Choosing this value means that you want this service to be reachable only from inside of the cluster.
-
NodePort: on top of having a cluster-internal IP, expose the service on a port on each node of the cluster (the same port on each node). You’ll be able to contact the service on any <NodeIP>:NodePort address.
-
LoadBalancer: on top of having a cluster-internal IP and exposing service on a NodePort also, ask the cloud provider for a load balancer which forwards to the Service exposed as a <NodeIP>:NodePort for each Node.
As you could see on Start MySQL service section, the MySql service file doesn’t contain any ServiceType field. For that reason, the default value is ClusterIP which means that the MySql service can be accessed inside the Cluster.
In the other hand, not all Kubernetes Provider supports the LoadBalancer type. On cloud providers which support external load balancers, setting the type field to "LoadBalancer" will provision a load balancer for your Service.
Do show how to access WildFly outside Kubernetes, we will need to use NodePort type which exposes your service on an external port on all nodes in your cluster.
Let’s see how it works.
-
Create a WildFly service of NodePort type
./cluster/kubectl.sh create -f ../../attendees/kubernetes/app-wildfly-service.yaml
You have exposed your service on an external port on all nodes in your
cluster. If you want to expose this service to the external internet, you may
need to set up firewall rules for the service port(s) (tcp:30140) to serve traffic.
See http://releases.k8s.io/HEAD/docs/user-guide/services-firewalls.md for more details.
services/wildfly-service
Note that it will reply with the port that was opened on each node of the cluster. Now you can use the combination between the node ip and the service port to access the service.
-
Get the IP of the node
cluster/kubectl.sh get nodes
NAME LABELS STATUS
10.245.1.3 kubernetes.io/hostname=10.245.1.3 Ready
-
Get the PORT of the service
cluster/kubectl.sh describe se wildfly-service
Name: wildfly-service
Namespace: default
Labels: context=docker-k8s-lab,name=wildfly
Selector: context=docker-k8s-lab,name=wildfly
Type: NodePort
IP: 10.247.39.239
Port: <unnamed> 8080/TCP
NodePort: <unnamed> 30140/TCP
Endpoints: 10.246.88.7:8080
Session Affinity: None
No events.
Note the NodePort value and now you can access the URL: http://10.245.1.3:30140/employees/
10.5. Deploy Java EE Application (one configuration file)
Kubernetes allow multiple resources to be specified in a single configuration file. This allows to create a “Kubernetes Application” that can consists of multiple resources easily.
Deploy Java EE Application (multiple configuration files) showed how to deploy the Java EE application using multiple configuration files. This application can be delpoyed using a single configuration file as well.
-
Start the application using the configuration file:
apiVersion: v1
kind: Pod
metadata:
name: mysql-pod
labels:
name: mysql-pod
context: docker-k8s-lab
spec:
containers:
-
name: mysql
image: mysql:latest
env:
-
name: "MYSQL_USER"
value: "mysql"
-
name: "MYSQL_PASSWORD"
value: "mysql"
-
name: "MYSQL_DATABASE"
value: "sample"
-
name: "MYSQL_ROOT_PASSWORD"
value: "supersecret"
ports:
-
containerPort: 3306
----
apiVersion: v1
kind: Service
metadata:
name: mysql-service
labels:
name: mysql-pod
context: docker-k8s-lab
spec:
ports:
# the port that this service should serve on
- port: 3306
# label keys and values that must match in order to receive traffic for this service
selector:
name: mysql-pod
context: docker-k8s-lab
----
apiVersion: v1
kind: ReplicationController
metadata:
name: wildfly-rc
labels:
name: wildfly
context: docker-k8s-lab
spec:
replicas: 1
template:
metadata:
labels:
name: wildfly
context: docker-k8s-lab
spec:
containers:
- name: wildfly-rc-pod
image: arungupta/wildfly-mysql-javaee7:k8s
ports:
- containerPort: 8080
Notice that each section, one each for MySQL Pod, MySQL Service, and WildFly Replication Controller, is separated by ----.
-
Start the application:
./cluster/kubectl.sh create -f ../../attendees/kubernetes/app.yaml
pods/mysql-pod
services/mysql-service
replicationcontrollers/wildfly-rc
-
Access the application using Access the application (from inside a node) or Access the application (using Services).
10.6. Rescheduling Pods
Replication Controller ensures that specified number of pod “replicas” are running at any one time. If there are too many, the replication controller kills some pods. If there are too few, it starts more.
WildFly Replication Controller is already running with one Pod. Lets delete this Pod and see how a new Pod is automatically rescheduled.
-
Find the Pod’s name:
./cluster/kubectl.sh get po
NAME READY STATUS RESTARTS AGE
wildfly-rc-w2kk5 1/1 Running 0 6m
-
Delete the Pod:
./cluster/kubectl.sh delete po wildfly-rc-w2kk5
pods/wildfly-rc-w2kk5
Status of the Pods can be seen in another shell:
./cluster/kubectl.sh get -w po
NAME READY STATUS RESTARTS AGE
wildfly-rc-w2kk5 1/1 Running 0 2m
NAME READY STATUS RESTARTS AGE
wildfly-rc-xz6wu 0/1 Pending 0 2s
wildfly-rc-xz6wu 0/1 Pending 0 2s
wildfly-rc-xz6wu 0/1 Pending 0 12s
wildfly-rc-xz6wu 0/1 Running 0 14s
wildfly-rc-xz6wu 1/1 Running 0 22s
Notice how Pod with name “wildfly-rc-w2kk5” was deleted and a new Pod with the name “wildfly-rc-xz6wu” was created.
10.7. Scaling Pods
Replication Controller allows dynamic scaling up and down of Pods.
-
Scale up the number of Pods:
./cluster/kubectl.sh scale --replicas=2 rc wildfly-rc
scaled
-
Status of the Pods can be seen in another shell:
./cluster/kubectl.sh get -w po
NAME READY STATUS RESTARTS AGE
wildfly-rc-bgtkg 1/1 Running 0 3m
NAME READY STATUS RESTARTS AGE
wildfly-rc-bymu7 0/1 Pending 0 2s
wildfly-rc-bymu7 0/1 Pending 0 2s
wildfly-rc-bymu7 0/1 Pending 0 2s
wildfly-rc-bymu7 0/1 Running 0 3s
wildfly-rc-bymu7 1/1 Running 0 12s
Notice a new Pod with the name “wildfly-rc-bymu7” is created.
-
Scale down the number of Pods:
./cluster/kubectl.sh scale --replicas=1 rc wildfly-rc
scaled
-
Status of the Pods using
-wis not shown correctly #11338. But status of the Pods can be seen correctly as:
./cluster/kubectl.sh get po
NAME READY STATUS RESTARTS AGE
wildfly-rc-bgtkg 1/1 Running 0 9m
Notice only one Pod is running now.
10.8. Application Logs
-
Get a list of the Pods:
./cluster/kubectl.sh get po
NAME READY STATUS RESTARTS AGE
mysql-pod 1/1 Running 0 18h
wildfly-rc-w2kk5 1/1 Running 0 16h
-
Get logs for the WildFly Pod:
./cluster/kubectl.sh logs wildfly-rc-w2kk5
=> Starting WildFly server
=> Waiting for the server to boot
=========================================================================
JBoss Bootstrap Environment
JBOSS_HOME: /opt/jboss/wildfly
. . .
Logs can be obtained for any Kubernetes resources using this way. Alternatively, the logs can also be seen by logging into the node:
-
Log in to the node VM:
> vagrant ssh minion-1
Last login: Fri Jun 5 23:01:36 2015 from 10.0.2.2
[vagrant@kubernetes-minion-1 ~]$
-
Log in as root:
[vagrant@kubernetes-minion-1 ~]$ su -
Password:
[root@kubernetes-minion-1 ~]#
Default root password for VM images created by Vagrant is ‘vagrant’.
-
See the list of Docker containers running on this VM:
docker ps
-
View WildFly log as:
docker logs $(docker ps | grep arungupta/wildfly | awk '{print $1}')
-
View MySQL log as:
docker logs <CID>
10.9. Delete Kubernetes Resources
Individual resources (service, replication controller, or pod) can be deleted by using delete command instead of create command. Alternatively, all services and replication controllers can be deleted using a label as:
kubectl delete all -l context=docker-k8s-lab
10.10. Stop Kubernetes Cluster
> ./cluster/kube-down.sh
Bringing down cluster using provider: vagrant
==> minion-1: Forcing shutdown of VM...
==> minion-1: Destroying VM and associated drives...
==> master: Forcing shutdown of VM...
==> master: Destroying VM and associated drives...
Done
10.11. Debug Kubernetes Master
-
Log in to the master as:
vagrant ssh master
Last login: Wed Jul 15 20:36:32 2015 from 10.0.2.2
[vagrant@kubernetes-master ~]$
-
Log in as root:
[vagrant@kubernetes-master ~]$ su -
Password:
[root@kubernetes-master ~]#
Default root password for VM images created by Vagrant is ‘vagrant’.
-
Check the containers running on master:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
dc59a764953c gcr.io/google_containers/etcd:2.0.12 "/bin/sh -c '/usr/lo 20 hours ago Up 20 hours k8s_etcd-container.fa2ab1d9_etcd-server-kubernetes-master_default_7b64ecafde589b94a342982699601a19_2b69c4d5
b722e22d3ddb gcr.io/google_containers/kube-scheduler:d1107ff3b8fcdcbf5a9d78d9d6dbafb1 "/bin/sh -c '/usr/lo 20 hours ago Up 20 hours k8s_kube-scheduler.7501c229_kube-scheduler-kubernetes-master_default_98b354f725c1589ea5a12119795546ae_b81b9740
38a73e342866 gcr.io/google_containers/kube-controller-manager:fafaf8100ccc963e643b55e35386d713 "/bin/sh -c '/usr/lo 20 hours ago Up 20 hours k8s_kube-controller-manager.db050993_kube-controller-manager-kubernetes-master_default_f5c25224fbfb2de87e1e5c35e6b3a293_dcd4cb5d
01001de6409e gcr.io/google_containers/kube-apiserver:cff9e185796caa8b281e7d961aea828b "/bin/sh -c '/usr/lo 20 hours ago Up 20 hours k8s_kube-apiserver.7e06f4e1_kube-apiserver-kubernetes-master_default_829f8c23fd5fc7951253cac7618447fc_b39c0a5d
0f8ccb144ece gcr.io/google_containers/pause:0.8.0 "/pause" 20 hours ago Up 20 hours k8s_POD.e4cc795_kube-scheduler-kubernetes-master_default_98b354f725c1589ea5a12119795546ae_eb1efcac
0b8f527456c0 gcr.io/google_containers/pause:0.8.0 "/pause" 20 hours ago Up 20 hours k8s_POD.e4cc795_kube-apiserver-kubernetes-master_default_829f8c23fd5fc7951253cac7618447fc_5dd4dee7
39d9c41ab1a2 gcr.io/google_containers/pause:0.8.0 "/pause" 20 hours ago Up 20 hours k8s_POD.e4cc795_kube-controller-manager-kubernetes-master_default_f5c25224fbfb2de87e1e5c35e6b3a293_522972ae
d970ddff7046 gcr.io/google_containers/pause:0.8.0 "/pause" 20 hours ago Up 20 hours k8s_POD.e4cc795_etcd-server-kubernetes-master_default_7b64ecafde589b94a342982699601a19_fa75b27f
11. Common Docker Commands
Here is the list of commonly used Docker commands:
| Purpose | Command |
|---|---|
Image |
|
Build an image |
|
Install an image |
|
List of installed images |
|
List of installed images (detailed listing) |
|
Remove an image |
|
Remove all untagged images |
|
Remove all images |
|
Remove dangling images |
|
Containers |
|
Run a container |
|
List of running containers |
|
List of all containers |
|
Stop a container |
|
Stop all running containers |
|
List all exited containers with status 1 |
|
Remove a container |
|
Remove container by a regular expression |
|
Remove all exited containers |
|
Remove all containers |
|
Find IP address of the container |
|
Attach to a container |
|
Open a shell in to a container |
|
Get container id for an image by a regular expression |
|
12. Troubleshooting
12.1. Can’t resolve classroom.example.com
-
Make sure to add the instructor IP as DNS server to your system
-
On Windows temporarily disable IPv6 (we’re only supporting IPv4)
12.2. Network Timed Out
Depending upon the network speed and restrictions, you may not be able to download Docker images from Docker Hub. The error message may look like:
$ docker pull arungupta/wildfly-mysql-javaee7
Using default tag: latest
Pulling repository docker.io/arungupta/wildfly-mysql-javaee7
Network timed out while trying to connect to https://index.docker.io/v1/repositories/arungupta/wildfly-mysql-javaee7/images. You may want to check your internet connection or if you are behind a proxy.
This section provide a couple of alternatives to solve this.
12.2.1. Restart Docker Machine
It seems like Docker Machine gets into a strange state and restarting it fixes that.
docker-machine restart <MACHINE_NAME>
eval $(docker-machine env <MACHINE_NAME>)
12.2.2. Loading Images Offline
Images can be downloaded from a previously saved .tar file. All images required for this workshop can be downloaded from:
Load the tar file:
docker load -i <path to image tar file>
For example:
docker load -i arungupta-javaee7-hol.tar
Now docker images should show the image.
12.3. Cannot create Docker Machine on Windows
Double check, that you have the correct version of VirtualBox installed. Clear all host-adapter interfaces in Virtualbox before creating a new machine. Make sure to have git for windows in your path.
Are you not able to create Docker Machine on Windows?
Try starting a cmd with Administrator privileges and then give the command again.
12.4. No route to host
Accessing the WildFly and MySQL sample in Kubernetes gives 404 when you give the command curl http://10.246.1.23:8080/employees/resources/employees/.
This may be resolved by stopping the node and restarting the cluster again:
vagrant halt minion-1
./cluster/kube-up.sh
These commands need to be given in the ‘kubernetes’ directory.
12.5. Docker machine creation fails with an error about dial tcp: i/o timeout
If you get the following error when creating a docker machine
Error creating machine: Error in driver during machine creation: Get https://api.github.com/repos/boot2docker/boot2docker/releases: dial tcp: i/o timeout
Then you need to go to the boot2docker releases page on
And download the latest .iso
After that you can move that iso to the docker cache directory. This is located in ~/.docker/machine/cache on Mac & Linux and /Users/yourUserName/.docker/machine/cache on Windows.
Issue: https://github.com/docker/machine/issues/2186 is raised so that the docker-machine team can hopefully find a way around this.
13. References
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Docker Docs: http://docs.docker.com
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Kubernetes Docs: https://github.com/kubernetes/kubernetes/tree/master/docs
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JBoss and Docker: http://www.jboss.org/docker/
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Latest lab content: https://github.com/javaee-samples/docker-java